


kill the lights

by meowcosm



Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Anal Sex, Anxiety, Aphrodisiacs, Bottom Seteth, Consensual Aphrodisiac Use, Licking, M/M, Purring, Slight Monsterfucking, Strap-Ons, Trans Male Character
Language: English
Status: Completed
Published: 2020-04-26
Updated: 2020-04-26
Packaged: 2021-03-01 21:06:41
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,254
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23853538
Author URL: https://archiveofourown.org/users/meowcosm/pseuds/meowcosm
Summary: Seteth lives a life of vigilance, even around the people that he loves.Inadvertently, he finds a way to relax.
Relationships: My Unit | Byleth/Seteth
Comments: 2
Kudos: 54





	kill the lights

**Author's Note:**

> used a randomized kink generator to pick a subject for this and got aphrodisiacs, which i Literally Just Wrote About for another ship
> 
> still, don't fix what isn't broken

Sometimes, Seteth isn’t sure if he’s okay. 

It feels silly- foolish, even- to think along those lines, not after everything he’s seen. Each morning, he wakes up in his own bed, in his own territory. His flesh remaining unrendered, his head quite firmly perched on his shoulders- his identity, in its deepest truth, revealed only to the closest few. Flayn, too, sharing in the simple pleasures of a world without fear. 

There are an incalculable many, Seteth knows, who had such simple pleasures stolen away from them. In a life of near-constant violence, he’s come out of it rather fortunate. 

Even then, though, it’s hardly as if his body  _ understands _ that. In peaceful ages, the shadows that gather behind him still act with malice- at least until he’s turned around. To be looked at too deeply sends him sick, to be touched without expecting it makes his body lurch. 

The flesh, it turns out, can hold suspicions much longer than the mind wishes it did.

There are times, though, when it’s easier. Things, too, that make him want, that make him ache- that activate whatever inside him might supersede fear, replacing all of the aches and stopping-points in his body. 

At first, Seteth had taken the “potent herbal extract” Byleth had obtained from some less-than-reputable market merchant to be nought more than a placebo. Caution, he’d advised, was the wisest state of mind. For that reason, it had spent months tucked away in Seteth’s personal apothecary, specially catered for Nabatean biology. Ignored each time he’d reached in for the remedy for a cold, or the strong clippers necessary to trim the ever-emergent sharpness of his nails. Still, he’d never had the heart to throw it away- Byleth had invested some considerable wealth into it, and though Seteth considered such a decision foolish in the first place, he’d learned the hard way that someone’s trinkets might one day be all that’s left of them. 

The first time, then, had been an accident. 

While Seteth was perfectly content to use human medicines, per se, he’d taken great care to commit a list of unsuitable ingredients to heart- certain botanicals, mostly, which could interfere quite drastically with his body. Each time he’d been prescribed something by Manuela, he’d inquire about the contents in depth, asked her to examine the contents until everything could be ruled out. All of this, he supposed, must have made him seem rather suspect- still, as long as he was in charge, all of this could be written off as allergies. When there was nothing left suitable for him, during the days of post-war shortages, he’d resorted to his own personal stock of medicine. 

That had been where the real problems began. In the desperate search for something that wouldn’t likely make the gnawing pain of the healing wound on his leg even worse, he’d gone through most of his medicines- all in a rather careless fashion. Had mistaken, in a path of wretched adrenaline, the strange substance of Byleth’s acquisition for his own typical tincture. 

To its credit; it had certainly fulfilled the purpose Seteth had sought it for, albeit by making it feel like every single part of his body was in some strange place between ecstasy and emptiness. Indeed, in the relentless grinding and evident desperation he’d demonstrated to Byleth upon his return to their shared quarters, he’d felt scarcely anything, save for the unbearable warmth of his body against Byleth and how desperate, almost wanton, he’d been. 

It had been easier, then. Easier to let go and focus on what he wanted; things he’d known he needed, but flinched away from. And though Byleth, believing him out of his mind, had only laid him down in bed until the effects subsided, his want hardly did the same. Somehow, despite everything, he’d enjoyed it; his sacrifice to something more base, more carnal, than he’d felt comfortable allowing himself for a long time. Perhaps it was embarrassing to have rutted so fiercely against Byleth’s thighs, to have pleaded so breathily for Byleth to split him apart on one of his toys- but he had spoken no untruth. 

Sometimes, Seteth wants. Not to pretend everything is normal, but to live, if only for a brief while, on needy impulse. It helps, then, with Byleth poised over him, having picked out the largest and most domineering-looking tool in his arsenal, for Byleth to dip a single callused finger into the vial of silvery powder lying on the side-table. For Seteth to lick it off, rough tongue sweeping over each fine crevasse, sharp canines brushing against the softer points of flesh. 

It always works, eventually. Leaves Seteth lying on his stomach, prone, as Byleth slips slick fingers into his hole, and Seteth feels nothing but the feverish ache of his cock and the blunt pressure of Byleth slowly, carefully, working past the loosening coil of muscle. He tries to buck upwards, like he’ll be able to have Byleth hit his prostate sooner, but Byleth only pushes him back down again. Still, he increases the strength of his movements, and increases his pace, rubs the enticing softness of the fabric wrapped around his thighs on Seteth’s cock. 

Byleth always gets him so worked up. He has a mercenary’s patience, Seteth thinks, and if his strange little substance didn’t make orgasm much more elusive, he suspects he might come solely at the simple friction. But he wants, hungrily, and even in lust, he knows his desire well enough to moan at every deeply-wanted touch. To gasp, full of some static-filled fire, when Byleth works him open sufficiently enough to slip inside, parting him with confidence. 

“Is it alright?” Byleth inquires, voice still even. Seteth nods, an almost-violent shake of the head, moaning as he does. It’s all the encouragement Byleth needs- before Seteth can bring himself out of his fugue state of  _ wanting, needing  _ to speak a single word, Byleth is slipping deeper within. Slow, almost torturously, until he hits the point where Seteth is nearly straining inside- then, he thrusts down, towards Seteth’s stomach, a great and ragged pressure against his prostate. And though he can barely make it out through the silent storm inside of his head, he swears Byleth is moaning, yelping, calling his name as he thrusts, hip-strength carved over the course of years. With the tip of the strap pressed so tight against his most sensitive point, jutting into it, Byleth bucking up and down against him- Seteth’s cock strains, and it becomes harder than anything to not surrender. Not when he can feel the first few droplets of warm, sticky fluid spilling inside him, together with the knowledge that he’s been split so rough and firm that he’ll hardly be able to move the next morning. 

Still, it takes Byleth’s hand, stroking rigid down his cock, for Seteth to spend over the sheets, twitching as he does- Byleth, all the while, guiding him through his orgasm, waiting for him to be well and truly finished before pulling out. 

“Good, Seteth.” Though they float aimlessly in Seteth’s head, the words of praise hardly go amiss, and when Byleth reaches down after pulling out to stroke through Seteth’s hair, he can’t stop a primal purr from escaping his throat. 

And though he might feel bad at the knowledge that Byleth hasn’t finished himself, from the way Byleth’s soft touches excite him so, Seteth suspects it won’t be long before he’ll be able to offer something more. 

Everything considered, he can hardly wait. 

**Author's Note:**

> hope you enjoyed!! thank you v much for reading
> 
> find me at twitter @meowcosm where i talk abt seteths fat titties, and other less important stuff
> 
> \+ if you liked kudos/comments are appreciated :-)


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